The invention relates to a synthesis method of meloxicam, belonging to the field of medicine synthesis. The method comprises the following steps of: adding 4-hydroxyl-2-methyl-2H-1,2-benzothiazine-3-ethyl formate-1,1-dioxide and 2-amino-5-methylthiazole into dimethyl sulfoxide; reacting at a certain temperature while steaming out ethanol; after the reaction, adding a certain amount of ethanol into the reaction liquid; cooling and filtering to obtain a crude product of meloxicam; and recrystallizing the crude product to obtain a high-purity purified product of meloxicam.